This invention relates generally to semiconductor and component packaging technology and more particularly, it relates to a fixture for mounting a heat sink to a pin grid array (PGA) integrated circuit chip package disposed in a PGA carrier.
Over the past years, there has been an increasing need for high density packaging for large scale integration (LSI) devices. In response to this demand, there has been developed in the industry a common arrangement referred to in the art as a pin grid array (PGA) chip package. Typically, the PGA chip package includes a main body member having a generally rectangular or square configuration. A plurality of metal terminal pins extend from the top surface of the body member to protrude from its bottom surface. The plurality of pins are disposed in the form of rows and columns so as to provide a matrix array. In order to protect the terminal pins of the PGA packages from being bent, damaged or possible destruction during handling, testing and shipping, the PGA packages are generally mounted or loaded into some kind of chip carrier. One conventional kind of chip carrier in the art has a centrally disposed recess and releasable tabs extending from two opposite sides of the carrier forming what is generally known as a Murphy-type carrier.
The Murphy-type carriers are recognized as a provider of adequate protection for the terminal pins of the PGA package during handling and shipment. However, in order to overcome the problem of inferior heat dissipation experienced by such carriers, there has arisen the need of mounting a heat sink to the central portion of the top surface of the PGA package. The requirement for such heat dissipation is becoming more significantly important due to the advent of highly sophisticated integrated circuit chips having a higher degree of integration so as to maintain the temperature of the I.C. chips to be within its desired operating limits.
Typically, a small disc-shaped preform is used to attach the heat sink to the top surface of the PGA package which is already disposed in the Murphy-type carrier. One surface of the preform is placed onto the top surface of the PGA package, and then the heat sink is placed onto the other surface of the preform. It is generally required that the PGA package disposed in the carrier, preform and heat sink all be place in proper registration or vertical alignment prior to a heat curing process. The heat curing process is a bonding technique for permanently securing the heat sink to the PGA package so as to form an integral unit. It has been encountered heretofore the problem of visually aligning the PGA package, preform and heat sink prior to effecting such heat curing process.
It is therefore believed that what is needed is a fixture for mounting a heat sink to a PGA chip package disposed in a Murphy-type carrier so as to maintain vertical alignment and preload during a heat curing process. It would also be expedient to provide a fixture which is formed of a relatively simple construction and can be easily operated without the need of complicated, mechanism instructions for aligning of all of the components, but yet has enough strength to provide pressure on preform without deformation due to heat and to withstand normal physical handling as well as abuses in the production environment. The fixture should also be designed so as to facilitate stacking when needed as during the heat curing process, thereby reducing labor costs. The fixture of the present invention for mounting a heat sink to a PGA package or unit has been designed with all of these features which have been traditionally unavailable.